This invention relates generally to loading dock leveler assemblies and more particularly to a dock leveler assembly which when in one mode automatically produces a barrier to prevent material handling equipment from accidentally running off the exposed front end of the dock.
Loading dock leveler assemblies are used widely to facilitate the loading and unloading of various sized vehicles parked adjacent to a loading dock platform. Examples of loading dock leveler assemblies are disclosed in U.S. Pat. Nos. 3,583,014, 3,699,601, 3,728,753, 4,110,860, 4,257,137, 4,531,248, and 4,570,277. Such levelers compensate for the height variations between the loading dock platform and the bed of the vehicle with a pivotally mounted loading ramp having an extension plate or lip pivotally mounted on the front edge portion of the loading ramp.
In the practical implementation of the use of such dock levelers certain safety problems may occur. Loading dock personnel may inadvertently drive or push fork lift trucks or related material handling equipment off the exposed front end of the loading dock leveler when there is no vehicle parked adjacent the loading dock and the dock leveler ramp is disposed in a stored position wherein the exposed surface of the ramp is level with the dock platform surface.
Dock levelers have heretofore been provided to minimize the risk of such accidental run off. Such dock levelers utilize a lip pivotally fixed to the front edge of the ramp. The pivot axis of the lip is set back a substantial distance from the rear edge of the lip so that the rear section of the lip between the pivotal axis and the lip rear edge will project above the ramp surface and form a barrier. When the lip is in an extended cantilevered position, the rear section of the lip would still project angularly to a varying degree above the loading ramp surface unless the ramp surface and the exposed surface of the lip were coplanar. Thus, the continued projection of the lip rear section might seriously obstruct the loading and unloading operations.
However, there are circumstances where it is desirable to provide an automatic barrier to handling equipment run off when the dock leveler assembly is in a stored neutral position while allowing the entire length of the barrier to depend below the loading ramp when the dock leveler is in other positions. Such circumstances include situations where material must be loaded onto or unloaded from the extreme rear of the bed of the vehicle parked adjacent the loading dock and the placement of the material interferes with the use of the dock leveler assembly with the lip in a fully extended position resting on the rear of the vehicle bed. It is also advantageous to avoid the pinching area developed in levelers which utilize a lip having a barrier forming rear section which overlaps under certain operating conditions the loading ramp since a potential for entrapping equipment or personnel exists in such levelers.